Method and apparatus for assembling syringes



METHOD AND APPARATUS FOR ASSEMBLING SYRINGES Filed Sept. 20, 1963 Sept.6, 1966 L. L. SMOYER ETAL 2 Sheets-Sheet 1 FIG.

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P 1966 1.. SMOYER ETAL 3,270,483

METHOD AND APPARATUS FOR ASSEMBLING SYRINGES Filed Sept. 20, 1963 2Sheets-Sheet 2 ['76. 3 FIG. 4

INVENTORS y/aw United States Patent 3,270,483 METHOD AND APPARATUS FORASSEMBLING SYRINGES Loyd L. Smoyer and Jack D. Vail, Jr., Overland Park,

Kans., assignors to Richardson-Meme]! Inc., New York,

N.Y., a corporation of Delaware Filed Sept. 20, 1963, Ser. No. 310,361 4Claims. (Cl. 53-43) This invention relates to a method of inserting theplunger into the barrel of plastic syringes and to apparatus forperforming the method.

It is common practice, particularly in the veterinary field, to providedisposable syringes containing a measured amount of a medicament whichcan be dispensed from the syringe after which the syringe is discarded.These one-use syringes are usually made of an inexpensive plasticmaterial such as polyethylene, nylon, or cellulose acetate butyrate,which can be injection molded to within close dimensional tolerances.Since they are thrown away after one use, the cost of the syringe andfilling it are extremely important considerations.

One commercial method of filling these syringes is to insert the barrelof the syringe with the tip pointing downward in holders which aremounted on a tablewhich can be rotated. The syringe barrels may beinserted in the holders either automatically or by hand. The table isadvanced to a filling station and a liquid medicament is introduced intothe barrel of the syringe in predetermined amounts. When the syringe hasbeen filled to the desired extent, the table is advanced again and theplunger element of the syringe is inserted at another station.

The plunger element of the syringe must fit tightly in the barrel of thesyringe, like a piston in a cylinder of a gas engine, and beliquid-tight so that the liquid medicament will not bypass the pistonsection of the plunger when pressure is applied to force the medicamentfrom the syringe. Normally when the piston is inserted in the barrel ofthe syringe, pressure is developed because of compression of the air inthe barrel between the top of the medicament and the piston and theplunger cannot be inserted down close to the liquid level. Although theair will leak past the piston in time with continued pressure, themodern plastic syringes are highly efiicient and the air does not leakpast the piston portion of the plunger very fast. Accordingly, thesyringes cannot be assembled rapidly unless some means of venting theair is provided.

One prior art means of venting air is to drill a small hole in thebarrel of the syringe at a point above the liquid level of themedicament which allows air to escape. This is undesirable, however, asit provides an added step in the manufacture of the syringe and quiteoften, the medicament leaks out through the hole. Other means of ventingair from syringes have been used but, generally speaking, they are notconsidered satisfactory.

The present invention is concerned with an eifective method of rapidlyventing air from the barrel of the syringe while the plunger is beinginserted. It does not require that holes be drilled in the syringe andthe air venting operation can take place as fast as the machine can fillthe syringes with medicament. The apparatus is simple and inexpensiveand easily adjustable to syringes of various sizes. In order that thenature of the invention may be readily understood, reference is made tothe drawings in which:

FIGURE 1 is a plan view of a rotating table having a plurality ofsyringe holders positioned on its outer periphery. A part of the tableis broken away as being unnecessary to illustrate the invention.

FIGURE 2 is an elevational view of the essential working parts of anapparatus suitable for practicing the invention.

3,270,483- Patented Sept. 6, 1966 FIGURE 3 is an elevational view,partially in cross section, showing the apparatus in one of its workingpositions.

FIGURE 4 is also an elevational view, partly in cross section, takenalong a vertical plane at right angles to the view in FIGURE 3.

FIGURE 5 is a partial plan view partly in cross section taken along theline 55 of FIGURE 3.

FIGURE 6 is the same view as shown in FIGURE 5 with the air ventingapparatus in a different working position.

Referring again to FIGURE 2, it will be seen that the apparatus of thepresent invention includes a table 1 which is rotatable on its axis byany convenient means (not shown). The table is provided with a number ofspaced pockets adapted to receive holders 2 for syringes. The rotatabletable may be of any suitable diameter and may carry as many holders asare desired. The rotatable table and the insertable holders areconventional with automatic tube filling equip-ment and are not a partof the present invention. A cross section of the holders is shown tobetter advantage in FIGURES 3 and 4.

A syringe barrel 3, shown to best advantage in FIG- URES 3 and 4, isinserted into the holders as shown. The syringe is held at proper heightby a ledge 4 which may also hold shims (not shown) to adjust the heightof the syringe barrel as desired. The tip of the syringe is sealed by acap 5 when the filling operation takes place.

As stated above, a liquid medicament 6 is filled into the barrel of thesyringe by hand or with automatic equipment to a predetermined height 7,FIGURE 4. This is usually done while at a station some distance aroundthe periphery of the table from the air venting tation where theapparatus of the present invention is located. As the partially filledsyringe is being advanced by stages around the table, the plunger 8 isinserted into the barrel of the syringe as far as it can be forced byhand. Invariably, however, there is a space 9 filled with air betweenthe upper level 7 of the medicament and the lower face of the piston 10.This is the .air space that must be vented.

To vent the air space in accordance with the present invention, thesyringe with the partially inserted plunger is advanced to a stationover which the apparatus of the present invention operates as shown inFIGURES 1 and 2. The air venting apparatus comprises an element 11 withan adjustable head 12 which can be forced against the barrel of thesyringe at a point just above the top of the holder 2 as shown in FIGURE3. The movement of the compressing element 12 is brought about by meansof air operating a piston in cylinder 13. Air flowing through line 16forces the piston with its connecting rod 11 toward the syringe. Airentering through line 17 allows the piston within the cylinder 13 towithdraw the compressing element from the barrel of the syringe at theend of the cycle. Air operating the piston in the cylinder 13 may be ofabout 10 to 40 pounds per square inch pressure. A backing-up element 14with adjusting screw 15 is provided so that when force is appliedagainst the barrel of the syringe by the plunger, it is not tipped inthe holder. The backing-up element also makes it possible to apply thecorrect amount of force necessary to deform the barrel.

The action of the compressing elements is more clearly shown in FIGURE5. In this view the barrel of the syringe has been compressed slightly,about of an inch in the case of a 4 inch syringe, and is forced out ofround into an oval shape. Air escapes through the space 19 that iscreated. The syringe being made of a plastic material is easily deformedin the manner described and When the pressure is relieved, as shown inFIGURE 6,

the deformed parts of the syringe spring back to normal shape.

The plunger of the syringe is seated in proper position by means of avertically-acting piston within cylinder 22, as shown in FIGURE 2. Thispiston is also operated by means of air which flows through lines 23 and24. Air entering through line 23 causes the piston to move downward andthe connecting rod 21, which has an adjusting screw 28 is forced againstthe top of the syringe plunger and pushes itinto the barrel of thesyringe to a predetermined position. As will be noted, air enterscylinder 13 through line 16 simultaneously with air entering cylinder 22through line- 23, both feeding from line 25. Also, as will be seen fromFIGURE 2, air entering through line 17 will force the barrel squeezingmeans away from the syringe and air entering cylinder 22 through line 24will raise the plunger seating means. The assembled unit may then bemoved from the air venting station.

Cylinders 13 and 22 may be mounted on adjustable brackets 29and- 30,respectively, to enable additional adjustments so that the mechanism canhandle syringes of many d-iiferent sizes.

Air is supplied to lines 25 and 27 through a solenoid air valve 18 whichis controlled with microswitches. One microswitch 31 is placed'so thatwhen the syringe holder" arrives at the air venting station, therotation of the table will stop and air will be introduced into line 25from valve 18. This causes the connecting rod 21' to move downwardly andconnecting rod 11 to move toward'the barrel of the syringe so that thesyringe is compressed slightly and theplunger is pushed downsimultaneously. When the plunger has been pushed downwardly to thedesired position, microswitch 32 is activated which in turn operatesvalve-18 and causes air to flow through line 27 which raises theconnecting rod 21 and withdraws the compressing element fromcontaot'with the barrel of the syringe. The table is then rotated, thecompleted syringe is withdrawn, and another partially assembled syringeis moved into the air relieving station.

As will be seen from the foregoing description, the syringe assemblingdevice of the present invention is relatively simple in construction andoperation. The equipment used for filling syringes is standard and canbe obtained from several sources. The units are constructed to operateso that the table i turned from station to'station, stopping for a fewseconds at each station for an operation such as filling. The presentinvention can be added to these commercially available units without anyreconstruction of the tube filling equipment, or modifying the manner inwhich it operates.

What is claimed is:

1. A method of inserting plungers into syringes having a round resilientbarrel and being partially filled with a liquid which comprisessqueezing the barrel of'the syringe at a point above the level of saidliquid whereby the shape. of the barrel is deformed from its round to anoblong shape while simultaneously inserting the plunger into the barrelof said syringe, the air in the barrel of said syringe being allowed toescape through the passage created by said deformation of shape.

2. A method of inserting a plunger into the round barrel of a syringemade [of resilient plastic material which is partly filled with a liquidwhich comprises pushing against one side of the syringe barrel at aposition a short distance above the level of'the liquid in the barrelwhile supporting the opposite side to'thereby change the crosssectionalshape of the barrel from round to oblong thus providing an escapepassage for air within the barrel of the syringe over the liquid thereinand simultaneously inserting the plunger in the barrel of said syringeby pressing downward on the plunger.

3. Apparatus for inserting plungers into resilient syringes whichcomprises a holder in which the lower part of the syringe barrel isinserted, means for bringing pressure against the outer surface of thebarrel of the syringe in said holder at a point above the level of aliquid in said syringe said pressure being applied at right angles tothe vertical axis of the barrel of the syringe, means to support theopposite side of the syringe at a point opposite the side of the syringeat which pressure is applied while said pressure is being appliedthereby making it possible to change the cross-sectional shape of thebarrel at the point. where the pressure is being applied from round tooblong thus providing a passageway for the escape of air within thebarrelof said syringe above the level'of the liquid therein whilepressure is being exerted on the syringe and the plunger is beinginserted, and means to push a plunger for said syringe into the barrelpast the point at which pressure is being applied.

4. Apparatus for seating plungers in resilient syringes which comprisesa holder adapted to hold a syringe barrel in upright position with asubstantial part of the upper section of the syringe barrelunobstructed, means for bringing pressure against the outer barrel ofthe syringe in said holder at .a position above the level of a liquid inthe syringe, means opposite said pressure applying means adapted forholding the syringe and resisting pressure thereon while pressure isbeing applied, means for pressing down on a partially inserted plungerin said syringe operable simultaneously with the pressure applyingmeans, means tostop the downward motion of said plunger seating memberat a predetermined point, and means to simultaneously withdraw thepressure applying member and plunger-seating member.

References Cited bythe Examiner UNITED STATES PATENTS 2,738,118 3/1956Hall- 533l9 X 2,903,832 9/1959 Graff et ah 53-320 3,060,652 10/1962Eckman 5322 3,073,319 1/1963 Sperber 29-453 X CHARLIE T. MOON, PrimaryExaminer.

1. A METHOD OF INSERTING PLUNGERS INTO SYRINGES HAVING A ROUND RESILIENTBARREL AND BEING PARTIALLY FILLED WITH A LIQUID WHICH COMPRISESSQUEEZING THE BARREL OF THE SYRINGE AT A POINT ABOVE THE LEVEL OF SAIDLIQUID WHEREBY THE SHAPE OF THE BARREL IS DEFORMED FROM ITS ROUND TO ANOBLONG SHAPE WHILE SIMULTANEOUSLY INSERTING THE PLUNGER INTO THE BARRELOF SAID SYRINGE, THE AIR IN THE BARREL OF SAID SYRINGE BEING ALLOWED TOESCAPE THROUGH THE PASSAGE CREATED BY SAID DEFORMATION OF SHAPE. 3.APPARATUS FOR INSERTING PLUNGERS INTO RESILIENT SYRINGES WHICH COMPRISESA HOLDER IN WHICH THE LOWER PART OF THE SYRINGE BARREL IS INSERTED,MEANS FOR BRINGING PRESSURE AGAINST THE OUTER SURFACE OF THE BARREL OFTHE SYRINGE IN SAID HOLDER AT A POINT ABOVE THE LEVEL OF A LIQUID INSAID SYRINGE SAID PRESSURE BEING APPLIED AT RIGHT ANGLES TO THE VERTICALAXIS OF THE BARREL OF THE SYRINGE, MEANS TO SUPPORT THE OPPOSITE SIDE OFTHE SYRINGE AT A POINT OPPOSITE THE SIDE OF THE SYRINGE AT WHICHPRESSURE IS